Preparation of functional polymers phosphorus-containing organometal initiators

ABSTRACT

A method for preparing a functionalized polymer, the method comprising: polymerizing conjugated diene monomer, optionally together with comonomer, using a phosphorus-containing organometal initiator.

This application claims the benefit of U.S. Provisional Application Ser.No. 61/640,915, filed on May 1, 2012, which is incorporated herein byreference.

FIELD OF THE INVENTION

One or more embodiments of the present invention are directed toward thepreparation of functional polymers by employing phosphorus-containingorganometal initiators.

BACKGROUND OF THE INVENTION

Anionic polymerization techniques have been used to synthesize polymersthat are useful in the manufacture of tires. Using these techniques,certain organometallic compounds can be used to initiate thepolymerization of monomer such as conjugated diene monomer. Due to themechanism by which the initiation and polymerization proceeds, theorganometallic compound adds to monomer to form a polymer chain whereinthe organo substituent of the initiator is attached as the head group ofthe polymer. Common initiators include organo lithium species such asn-butyl lithium.

Certain initiators impart a functional group to the polymer. Thesefunctional groups may include a heteroatom or metal that can have adesirable impact on the polymer or compositions containing the polymer.For example, where the polymers are employed in the manufacture of tiretreads, the functional group can lower the hysteresis loss of the treadvulcanizate. This lowering of hysteresis loss may result frominteraction between the functional group and the filler, although othermechanisms have also been proposed.

Tributyl tin lithium compounds have been used to initiate conjugateddienes (optionally together with copolymerizable monomer) to formvulcanizable polymers (i.e., rubber) that, when used in treads, has adesirable impact on the performance of the tread. Likewise, lithiatedcyclic imines (e.g., lithio hexamethyleneimine) have also been used toinitiate the polymerization of similar polymers and provide rubber withdesirable performance in tire treads. Still other examples includelithiated thioacetals (e.g., 2-lithio-1,3-dithianes). Still further, theuse of lithium dialkylphosphines in conjunction with phosphine oxidemodifiers have been proposed.

The selection of useful initiator compounds, however, is not trivial.This is especially true where there is a desire to select initiatorcompounds that have a desirable impact on filled rubber compositions orvulcanizates, such as tire treads. Indeed, the prior art only includes afew types of compounds that are useful. This difficulty derives fromseveral factors. For example, the anionic polymerization of conjugateddienes is sensitive, and many compounds or substituents can poison thepolymerization system. And, the selection of substituents or functionalgroups that can impact filled compositions, such as tire treads, isdifficult to predict.

Because functional initiators remain desirable, particularly for thesynthesis for functionalized polymers that are used in the manufactureof tires, there is a continued desire to identify initiators that canlead to technologically useful polymers and that have desirable impacton filled rubber compositions and/or vulcanizates.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention provide a method forpreparing a functionalized polymer, the method comprising: polymerizingconjugated diene monomer, optionally together with comonomer, using aphosphorus-containing organometal initiator.

Still other embodiments of the present invention provide a method forpreparing a polymer, the method comprising: preparing an initiator byreacting a vinyl organophosphine with an organometal compound; andpolymerizing conjugated diene monomer, optionally together withcomonomer, by initiating the polymerization of the monomer with theinitiator.

Still other embodiments of the present invention provide afunctionalized polymer defined by the Formula V:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, where R⁶ is abond or a divalent organic group, P is a phosphorus atom, π is a polymerchain, and ω is a hydrogen atom, a terminal functional group, or amultivalent coupling group.

A functionalized polymer defined by the Formula VI:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, where R⁶ is abond or a divalent organic group, P is a phosphorus atom, π is a polymerchain, and ω is a hydrogen atom, a terminal functional group, or amultivalent coupling group.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS Introduction

Aspects of the present invention are based, at least in part, on thediscovery of a method for initiating the anionic polymerization of dienemonomer, optionally together with comonomer, using phosphorus-containingorganometal compounds. While the prior art contemplates the use oflithium dialkyl phosphides, which are lithiated phosphines, the presentinvention employs an initiator where the phosphorus atom is directlybonded to a carbon atom. As a result, it is believed that the polymersproduced by practice of the present invention have aphosphorus-containing head group that is more stable than those proposedin the prior art.

Initiator

The phosphorus-containing organometal initiator employed in practice ofthe present invention may be prepared by reacting a vinylorganophosphine with an organometal compound.

In one or more embodiments, the vinyl organophosphine may be defined bythe formula I:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, and where R³, R⁴,and R⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group. In particularembodiments, R³, R⁴, and R⁵ are hydrogen atoms.

In one or more embodiments, the monovalent organic group is ahydrocarbyl group or substituted hydrocarbyl group. Examples ofhydrocarbyl groups or substituted hydrocarbyl groups include, but arenot limited to, alkyl, cycloalkyl, substituted cycloalkyl, alkenyl,cycloalkenyl, aryl, substituted aryl groups, and heterocyclic groups.The hydrocarbyl group may contain heteroatoms such as, but not limitedto, nitrogen, oxygen, silicon, tin, sulfur, boron, and phosphorousatoms. In one or more embodiments, the monovalent organic group mayinclude at least 1, or the minimum number of carbon atoms required toform a group, up to about 12 carbon atoms. The term substituted is usedin its conventional sense to refer to organic groups, such as alkylgroups, that replace a hydrogen atom in a parent organic group.

In one or more embodiments, types of vinyl organophosphines includevinyldihydrocarbyl phosphines,dihydrocarbyl(2,2-dihydrocarbyl-1-hydrocarbylvinyl)phosphines,dihydrocarbyl(2,2-dihydrocarbylvinyl)phosphines,dihydrocarbyl(2-hydrocarbylvinyl)phosphines,dihydrocarbyl(2-hydrocarbyl-1-hydrocarbylvinyl)phosphines, anddihydrocarbyl(1-hydrocarbylvinyl)phosphines.

Specific examples of vinyldihydrocarbyl phosphines include vinyldiphenylphosphine, vinyldicyclohexylphosphine,vinyldicyclopentylphosphine, vinyldimethylphosphine,vinyldiethylphosphine, vinyldi-n-propylphosphine,vinyldi-t-butylphosphine, vinyldi-n-octylphosphine,vinyldi-n-dodecylphosphine, vinyldipiperidylphosphine,vinyldipyrrolidylphosphine, vinyldipyridylphosphine, and vinyldipyrrylphosphine.

Specific examples ofdihydrocarbyl(2,2-dihydrocarbyl-1-hydrocarbylvinyl)phosphines includedimethyl(2,2-diphenyl-1-methylvinyl)phosphine,diethyl(2,2-diphenyl-1-methylvinyl)phosphine,di-n-propyl(2,2-diphenyl-1-methylvinyl)phosphine,di-t-butyl(2,2-diphenyl-1-methylvinyl)phosphine,di-n-octyl(2,2-diphenyl-1-methylvinyl)phosphine,di-n-dodecyl(2,2-diphenyl-1-methylvinyl)phosphine,diphenyl(2,2-diphenyl-1-methylvinyl)phosphine,dicyclohexyl(2,2-diphenyl-1-methylvinyl)phosphine,dicyclopentyl(2,2-diphenyl-1-methylvinyl)phosphine,dipiperidyl(2,2-diphenyl-1-methylvinyl)phosphine,dipyrrolidyl(2,2-diphenyl-1-methylvinyl)phosphine,dipyridyl(2,2-diphenyl-1-methylvinyl)phosphine,dipyrryl(2,2-diphenyl-1-methylvinyl)phosphine,dimethyl(2,2-diethyl-1-ethylvinyl)phosphine,diethyl(2,2-diethyl-1-ethylvinyl)phosphine,di-n-propyl(2,2-diethyl-1-ethylvinyl)phosphine,di-t-butyl(2,2-diethyl-1-ethylvinyl)phosphine,di-n-octyl(2,2-diethyl-1-ethylvinyl)phosphine,di-n-dodecyl(2,2-diethyl-1-ethylvinyl)phosphine,diphenyl(2,2-diethyl-1-ethylvinyl)phosphine,dicyclohexyl(2,2-diethyl-1-ethylvinyl)phosphine,dicyclopentyl(2,2-diethyl-1-ethylvinyl)phosphine,dipiperidyl(2,2-diethyl-1-ethylvinyl)phosphine,dipyrrolidyl(2,2-diethyl-1-ethylvinyl)phosphine,dipyridyl(2,2-diethyl-1-ethylvinyl)phosphine,dipyrryl(2,2-diethyl-1-ethylvinyl)phosphine,dimethyl(2,2-dicyclohexyl-1-propylvinyflphosphine,diethyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,di-n-propyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,di-t-butyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,di-n-octyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,di-n-dodecyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,diphenyl(2,2-dicyclohexyl-1-propylvinyflphosphine,dicyclohexyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,dicyclopentyl(2,2-dicyclohexyl-1-propylvinyflphosphine,dipiperidyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,dipyrrolidyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,dipyridyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,dipyrryl(2,2-dicyclohexyl-1-propylvinyl)phosphine,dimethyl(2,2-dipyridyl-1-ethylvinyl)phosphine,diethyl(2,2-dipyridyl-1-ethylvinyl)phosphine,di-n-propyl(2,2-dipyridyl-1-ethylvinyl)phosphine,di-t-butyl(2,2-dipyridyl-1-ethylvinyl)phosphine,di-n-octyl(2,2-dipyridyl-1-ethylvinyl)phosphine,di-n-dodecyl(2,2-dipyridyl-1-ethylvinyl)phosphine,diphenyl(2,2-dipyridyl-1-ethylvinyl)phosphine,dicyclohexyl(2,2-dipyridyl-1-ethylvinyl)phosphine,dicyclopentyl(2,2-dipyridyl-1-ethylvinyl)phosphine,dipiperidyl(2,2-dipyridyl-1-ethylvinyl)phosphine,dipyrrolidyl(2,2-dipyridyl-1-ethylvinyl)phosphine,dipyridyl(2,2-dipyridyl-1-ethylvinyl)phosphine, anddipyrryl(2,2-dipyridyl-1-ethylvinyl)phosphine.

Specific examples of dihydrocarbyl(2,2-dihydrocarbylvinyl)phosphinesinclude dimethyl(2,2-diphenylvinyl)phosphine,diethyl(2,2-diphenylvinyl)phosphine,di-n-propyl(2,2-diphenylvinyl)phosphine,di-t-butyl(2,2-diphenylvinyl)phosphine,di-n-octyl(2,2-diphenylvinyl)phosphine,di-n-dodecyl(2,2-diphenylvinyl)phosphine,diphenyl(2,2-diphenylvinyl)phosphine,dicyclohexyl(2,2-diphenylvinyl)phosphine,dicyclopentyl(2,2-diphenylvinyl)phosphine,dipiperidyl(2,2-diphenylvinyl)phosphine,dipyrrolidyl(2,2-diphenylvinyl)phosphine,dipyridyl(2,2-diphenylvinyl)phosphine,dipyrryl(2,2-diphenylvinyl)phosphine,dimethyl(2,2-diethylvinyl)phosphine, diethyl(2,2-diethylvinyl)phosphine,di-n-propyl(2,2-diethylvinyl)phosphine,di-t-butyl(2,2-diethylvinyl)phosphine,di-n-octyl(2,2-diethylvinyl)phosphine,di-n-dodecyl(2,2-diethylvinyl)phosphine,diphenyl(2,2-diethylvinyl)phosphine,dicyclohexyl(2,2-diethylvinyl)phosphine,dicyclopentyl(2,2-diethylvinyl)phosphine,dipiperidyl(2,2-diethylvinyl)phosphine,dipyrrolidyl(2,2-diethylvinyl)phosphine,dipyridyl(2,2-diethylvinyl)phosphine,dipyrryl(2,2-diethylvinyl)phosphine,dimethyl(2,2-dicyclohexylvinyl)phosphine,diethyl(2,2-dicyclohexylvinyl)phosphine,di-n-propyl(2,2-dicyclohexylvinyl)phosphine,di-t-butyl(2,2-dicyclohexylvinyl)phosphine,di-n-octyl(2,2-dicyclohexylvinyl)phosphine,di-n-dodecyl(2,2-dicyclohexylvinyl)phosphine,diphenyl(2,2-dicyclohexylvinyl)phosphine,dicyclohexyl(2,2-dicyclohexylvinyl)phosphine,dicyclopentyl(2,2-dicyclohexylvinyl)phosphine,dipiperidyl(2,2-dicyclohexylvinyl)phosphine,dipyrrolidyl(2,2-dicyclohexylvinyl)phosphine,dipyridyl(2,2-dicyclohexylvinyl)phosphine,dipyrryl(2,2-dicyclohexylvinyl)phosphine,dimethyl(2,2-dipyridylvinyl)phosphine,diethyl(2,2-dipyridylvinyl)phosphine,di-n-propyl(2,2-dipyridylvinyl)phosphine,di-t-butyl(2,2-dipyridylvinyl)phosphine,di-n-octyl(2,2-dipyridylvinyl)phosphine,di-n-dodecyl(2,2-dipyridylvinyl)phosphine,diphenyl(2,2-dipyridylvinyflphosphine,dicyclohexyl(2,2-dipyridylvinyl)phosphine,dicyclopentyl(2,2-dipyridylvinyl)phosphine,dipiperidyl(2,2-dipyridylvinyl)phosphine,dipyrrolidyl(2,2-dipyridylvinyl)phosphine,dipyridyl(2,2-dipyridylvinyl)phosphine, anddipyrryl(2,2-dipyridylvinyl)phosphine.

Specific examples of dihydrocarbyl(2-hydrocarbylvinyl)phosphines includedimethyl(2-phenylvinyl)phosphine, diethyl(2-phenylvinyl)phosphine,di-n-propyl(2-phenylvinyl)phosphine, di-t-butyl(2-phenylvinyl)phosphine,di-n-octyl(2-phenylvinyl)phosphine,di-n-dodecyl(2-phenylvinyl)phosphine, diphenyl(2-phenylvinyl)phosphine,dicyclohexyl(2-phenylvinyl)phosphine,dicyclopentyl(2-phenylvinyl)phosphine,dipiperidyl(2-phenylvinyl)phosphine,dipyrrolidyl(2-phenylvinyl)phosphine, dipyridyl(2-phenylvinyl)phosphine,dipyrryl(2-phenylvinyl)phosphine, dimethyl(2-ethylvinyl)phosphine,diethyl(2-ethylvinyl)phosphine, di-n-propyl(2-ethylvinyl)phosphine,di-t-butyl(2-ethylvinyl)phosphine, di-n-octyl(2-ethylvinyl)phosphine,di-n-dodecyl(2-ethylvinyl)phosphine, diphenyl(2-ethylvinyl)phosphine,dicyclohexyl(2-ethylvinyl)phosphine,dicyclopentyl(2-ethylvinyl)phosphine,dipiperidyl(2-ethylvinyl)phosphine, dipyrrolidyl(2-ethylvinyl)phosphine,dipyridyl(2-ethylvinyl)phosphine, dipyrryl(2-ethylvinyl)phosphine,dimethyl(2-cyclohexylvinyl)phosphine,diethyl(2-cyclohexylvinyl)phosphine,di-n-propyl(2-cyclohexylvinyl)phosphine,di-t-butyl(2-cyclohexylvinyl)phosphine,di-n-octyl(2-cyclohexylvinyl)phosphine,di-n-dodecyl(2-cyclohexylvinyl)phosphine,diphenyl(2-cyclohexylvinyl)phosphine,dicyclohexyl(2-cyclohexylvinyl)phosphine,dicyclopentyl(2-cyclohexylvinyl)phosphine,dipiperidyl(2-cyclohexylvinyl)phosphine,dipyrrolidyl(2-cyclohexylvinyl)phosphine,dipyridyl(2-cyclohexylvinyl)phosphine,dipyrryl(2-cyclohexylvinyl)phosphine, dimethyl(2-pyridylvinyl)phosphine,diethyl(2-pyridylvinyl)phosphine, di-n-propyl(2-pyridylvinyl)phosphine,di-t-butyl(2-pyridylvinyl)phosphine,di-n-octyl(2-pyridylvinyl)phosphine,di-n-dodecyl(2-pyridylvinyl)phosphine,diphenyl(2-pyridylvinyl)phosphine,dicyclohexyl(2-pyridylvinyl)phosphine,dicyclopentyl(2-pyridylvinyl)phosphine,dipiperidyl(2-pyridylvinyl)phosphine,dipyrrolidyl(2-pyridylvinyl)phosphine,dipyridyl(2-pyridylvinyl)phosphine, anddipyrryl(2-pyridylvinyl)phosphine.

Specific examples ofdihydrocarbyl(2-hydrocarbyl-1-hydrocarbylvinyl)phosphines includedimethyl(2-phenyl-1-methylvinyl)phosphine,diethyl(2-phenyl-1-methylvinyl)phosphine,di-n-propyl(2-phenyl-1-methylvinyl)phosphine,di-t-butyl(2-phenyl-1-methylvinyl)phosphine,di-n-octyl(2-phenyl-1-methylvinyl)phosphine,di-n-dodecyl(2-phenyl-1-methylvinyl)phosphine,diphenyl(2-phenyl-1-methylvinyl)phosphine,dicyclohexyl(2-phenyl-1-methylvinyl)phosphine,dicyclopentyl(2-phenyl-1-methylvinyl)phosphine,dipiperidyl(2-phenyl-1-methylvinyl)phosphine,dipyrrolidyl(2-phenyl-1-methylvinyl)phosphine,dipyridyl(2-phenyl-1-methylvinyl)phosphine,dipyrryl(2-phenyl-1-methylvinyl)phosphine,dimethyl(2-ethyl-1-ethylvinyl)phosphine,diethyl(2-ethyl-1-ethylvinyl)phosphine,di-n-propyl(2-ethyl-1-ethylvinyl)phosphine,di-t-butyl(2-ethyl-1-ethylvinyl)phosphine,di-n-octyl(2-ethyl-1-ethylvinyl)phosphine,di-n-dodecyl(2-ethyl-1-ethylvinyl)phosphine,diphenyl(2-ethyl-1-ethylvinyl)phosphine,dicyclohexyl(2-ethyl-1-ethylvinyl)phosphine,dicyclopentyl(2-ethyl-1-ethylvinyl)phosphine,dipiperidyl(2-ethyl-1-ethylvinyl)phosphine,dipyrrolidyl(2-ethyl-1-ethylvinyl)phosphine,dipyridyl(2-ethyl-1-ethylvinyl)phosphine,dipyrryl(2-ethyl-1-ethylvinyl)phosphine,dimethyl(2-cyclohexyl-1-propylvinyl)phosphine,diethyl(2-cyclohexyl-1-propylvinyl)phosphine,di-n-propyl(2-cyclohexyl-1-propylvinyl)phosphine,di-t-butyl(2-cyclohexyl-1-propylvinyl)phosphine,di-n-octyl(2-cyclohexyl-1-propylvinyl)phosphine,di-n-dodecyl(2-cyclohexyl-1-propylvinyl)phosphine,diphenyl(2-cyclohexyl-1-propylvinyl)phosphine,dicyclohexyl(2-cyclohexyl-1-propylvinyl)phosphine,dicyclopentyl(2-cyclohexyl-1-propylvinyl)phosphine,dipiperidyl(2-cyclohexyl-1-propylvinyl)phosphine,dipyrrolidyl(2-cyclohexyl-1-propylvinyl)phosphine,dipyridyl(2-cyclohexyl-1-propylvinyl)phosphine, dipyrryl(2,2-cyclohexyl-1-propylvinyl)phosphine,dimethyl(2-pyridyl-1-ethylvinyl)phosphine,diethyl(2-pyridyl-1-ethylvinyl)phosphine,di-n-propyl(2-pyridyl-1-ethylvinyl)phosphine,di-t-butyl(2-pyridyl-1-ethylvinyl)phosphine,di-n-octyl(2-pyridyl-1-ethylvinyl)phosphine,di-n-dodecyl(2-pyridyl-1-ethylvinyl)phosphine,diphenyl(2-pyridyl-1-ethylvinyl)phosphine,dicyclohexyl(2-pyridyl-1-ethylvinyl)phosphine,dicyclopentyl(2-pyridyl-1-ethylvinyl)phosphine,dipiperidyl(2-pyridyl-1-ethylvinyl)phosphine,dipyrrolidyl(2-pyridyl-1-ethylvinyl)phosphine,dipyridyl(2-pyridyl-1-ethylvinyl)phosphine, anddipyrryl(2-pyridyl-1-ethylvinyl)phosphine.

Specific examples of dihydrocarbyl(1-hydrocarbylvinyl)phosphines includedimethyl(1-methylvinyl)phosphine, diethyl(1-methylvinyl)phosphine,di-n-propyl(1-methylvinyl)phosphine, di-t-butyl(1-methylvinyl)phosphine,di-n-octyl(1-methylvinyl)phosphine,di-n-dodecyl(1-methylvinyl)phosphine, diphenyl(1-methylvinyl)phosphine,dicyclohexyl(1-methylvinyl)phosphine,dicyclopentyl(1-methylvinyl)phosphine,dipiperidyl(1-methylvinyl)phosphine,dipyrrolidyl(1-methylvinyl)phosphine, dipyridyl(1-methylvinyl)phosphine,dipyrryl(1-methylvinyl)phosphine, dimethyl(1-ethylvinyl)phosphine,diethyl(1-ethylvinyl)phosphine, di-n-propyl(1-ethylvinyl)phosphine,di-t-butyl(1-ethylvinyl)phosphine, di-n-octyl(1-ethylvinyl)phosphine,di-n-dodecyl(1-ethylvinyl)phosphine, diphenyl(1-ethylvinyl)phosphine,dicyclohexyl(1-ethylvinyl)phosphine,dicyclopentyl(1-ethylvinyl)phosphine,dipiperidyl(1-ethylvinyl)phosphine, dipyrrolidyl(1-ethylvinyl)phosphine,dipyridyl(1-ethylvinyl)phosphine, dipyrryl(1-ethylvinyl)phosphine,dimethyl(1-propylvinyl)phosphine, diethyl(1-propylvinyl)phosphine,di-n-propyl(1-propylvinyl)phosphine, di-t-butyl(1-propylvinyl)phosphine,di-n-octyl(1-propylvinyl)phosphine,di-n-dodecyl(1-propylvinyl)phosphine, diphenyl(1-propylvinyl)phosphine,dicyclohexyl(1-propylvinyl)phosphine,dicyclopentyl(1-propylvinyl)phosphine,dipiperidyl(1-propylvinyl)phosphine,dipyrrolidyl(1-propylvinyl)phosphine, dipyridyl(1-propylvinyl)phosphine,and dipyrryl(1-propylvinyl)phosphine.

In one or more embodiments, the organometal may be defined by theformula M R⁷ _(n), where M is a metal, R⁷ is a monovalent organic group,and n is equivalent to the valence of the metal. In one or moreembodiments, the metal is a group I or group II metal. In particularembodiments, the metal is lithium.

Because organolithium compounds are generally recognized as useful inanionic polymerizations, embodiments of the present invention will bedescribed based upon organolithium compounds or phosphorus-containingorganolithium compounds with the understanding that the skilled personwill be able to readily extend these teachings to other useful metals.Thus, embodiments of the invention are directed towardphosphorus-containing organolithium compounds prepared by reacting anorganolithium compound with vinyl organophosphine.

Exemplary types of organolithium compounds include hydrocarbyl lithiumsand substituted hydrocarbyl lithiums such as, but not limited to,alkyllithiums, cycloalkyllithiums, substituted cycloalkyllithiums,alkenyllithiums, cycloalkenyllithiums, substituted cycloalkenyllithiums,aryllithiums, allyllithiums, substituted aryllithiums, aralkyllithiums,alkaryllithiums, and alkynylllithiums, with each group preferablycontaining from 1 carbon atom, or the appropriate minimum number ofcarbon atoms to form the group, up to 20 carbon atoms. These hydrocarbylgroups may contain heteroatoms such as, but not limited to, nitrogen,boron, oxygen, silicon, sulfur, and phosphorus atoms. Specific examplesof useful organolithium compounds include t-butyllithium,n-butyllithium, and isobutyllithium.

As suggested above, the phosphorus-containing organometal compound(e.g., phosphorus-containing organolithium compound) is formed byreacting an organolithium compound with a vinyl organophosphine. Theamount of organolithium compound reacted with the vinyl organophosphinemay be represented as a molar ratio of organolithium to vinylorganophosphine (Li/P). In one or more embodiments, the molar ratio oforganolithium to vinyl organophosphine (Li/P) may be from 0.1:1 to 20:1,in other embodiments from 0.5:1 to 10:1, and in other embodiments from0.9:1 to 1.5:1.

In one or more embodiments, the phosphorus-containing organolithiumcompound is pre-formed, which includes reacting the organolithium andthe vinyl organophosphine compound in the presence of little to nomonomer. In one or more embodiments, the reaction between theorganolithium and the vinyl organophosphine takes place in the presenceof less than 1 mole percent, in other embodiments less than 0.5 molepercent, and in other embodiments less than 0.1 mole percent monomer tovinyl organophosphine. In particular embodiments, thephosphorus-containing organometal compound is formed in the substantialabsence of monomer, which refers to that amount of monomer or less thatwill not have an appreciable impact on the formation of thephosphorus-containing organometal or its use in anionic polymerization.

In one or more embodiments, the reaction between the organolithium andthe vinyl organophosphine compound takes place within a solvent. In oneor more embodiments, the solvent may be employed to either dissolve orsuspend one or more of the organolithium, the vinyl organophosphine, orthe phosphorus-containing organometal compound. Suitable solventsinclude those organic compounds that will not undergo polymerization orincorporation into a propagating polymer chain during polymerization ofmonomer in the presence of the phosphorus-containing organometalcompound. In one or more embodiments, these organic solvents are liquidat ambient temperature and pressure. Exemplary organic solvents includehydrocarbons with a low or relatively low boiling point such as aromatichydrocarbons, aliphatic hydrocarbons, and cycloaliphatic hydrocarbons.Non-limiting examples of aromatic hydrocarbons include benzene, toluene,xylenes, ethylbenzene, diethylbenzene, and mesitylene. Non-limitingexamples of aliphatic hydrocarbons include n-pentane, n-hexane,n-heptane, n-octane, n-nonane, n-decane, isopentane, isohexanes,isopentanes, isooctanes, 2,2-dimethylbutane, petroleum ether, kerosene,and petroleum spirits. And, non-limiting examples of cycloaliphatichydrocarbons include cyclopentane, cyclohexane, methylcyclopentane, andmethylcyclohexane. Mixtures of the above hydrocarbons may also be used.The low-boiling hydrocarbon solvents are typically separated from thepolymer upon completion of the polymerization. Other examples of organicsolvents include high-boiling hydrocarbons of high molecular weights,such as paraffinic oil, aromatic oil, or other hydrocarbon oils that arecommonly used to oil-extend polymers. Since these hydrocarbons arenon-volatile, they typically do not require separation and remainincorporated in the polymer. In yet other embodiments, examples ofuseful organic solvents include non-Zerwittenoff polar organic solvents.These solvents include, but are not limited to, ethers, such as dimethylether and diethyl ether, as well as cyclic ethers, such astetrahydrofuran (THF) and 2,2-bis(2′-tetrahydrofuryl)propane. Othernon-Zerwittenoff polar organic solvents include tertiary amines such astri-n-butyl amine.

In one or more embodiments, the pre-formed solution concentration of theorganolithium compound, the vinyl organophosphine compound, and/or thephosphorus-containing organometal compound within the solvent may befrom about 5 M (molar) to about 0.005 M, in other embodiments from about2 M to about 0.05 M, and in other embodiments from about 1.1 M to about0.075 M.

In one or more embodiments, the reaction between the organolithium andthe vinyl organophosphine compound may be conducted at a temperaturefrom about −78° C. to about 100° C., in other embodiments from about 0°C. to about 75° C., and in other embodiments from about 10° C. to about50° C. Also, this reaction can be conducted at atmospheric pressure. Inone or more embodiments, the reaction is conducted under anaerobicconditions.

In one or more embodiments, the reaction between the organolithium andthe vinyl organophosphine compound may take place in the presence of apolar coordinator. Compounds useful as polar coordinators include thosecompounds having an oxygen or nitrogen heteroatom and a non-bonded pairof electrons. Examples of useful polar coordinators include linear andcyclic oligomeric oxolanyl alkanes; dialkyl ethers of mono and oligoalkylene glycols (also known as glyme ethers); “crown” ethers; tertiaryamines; linear THF oligomers; and the like. Linear and cyclic oligomericoxolanyl alkanes are described in U.S. Pat. No. 4,429,091, which isincorporated herein by reference. Specific examples of compounds usefulas polar coordinators include 2,2-bis(2′-tetrahydrofuryl)propane,1,2-dimethoxyethane, N,N,N′,N′-tetramethylethylenediamine (TMEDA),tetrahydrofuran (THF), 1,2-dipiperidylethane, dipiperidylmethane,hexamethylphosphoramide, N—N′-dimethylpiperazine, diazabicyclooctane,dimethyl ether, diethyl ether, tri-n-butylamine, and mixtures thereof.When employed, the amount of polar coordinator present during thereaction between the organolithium and the vinyl organophosphine may befrom about 10,000 to about 0.001, in other embodiments from about 100 toabout 0.05, and in other embodiments from about 50 to about 0.1 molesper mole of the vinyl organophosphine.

Initiator Structure

While the vinyl organophosphines and the organometal are believed toreact to form the phosphorus-containing organometal initiator, the exactchemical structure resulting from the reaction between all species isnot known with a great deal of certainty. For example, the structure ofthe phosphorus-containing organometal initiators may depend on stabilityof the anion formed by a reaction with the organometal compound.

Without wishing to be bound by any particular theory, it is believedthat in one or more embodiments, vinyldihydrocarbyl phosphines react toform phosphorus-containing organolithium compounds that can be definedby the formula II:

where M is a metal, R¹ and R² are each independently monovalent organicgroups, or where R¹ and R² join to form a divalent organic group, whereR³, R⁴, and R⁵ are each independently hydrogen or monovalent organicgroups, or where R³ and R⁴ join to form a divalent organic group, andwhere R⁶ is a bond or a divalent organic group. In particularembodiments, R³, R⁴, and R⁵ are hydrogen atoms. In these or otherparticular embodiments, M is a group I (e.g. lithium) or group II (e.g.magnesium) metal. In these or other particular embodiments, R⁶ is adivalent organic group defined by the formula III:

where R¹, R², R³, R⁴, and R⁵ are defined as above, and x is an integerfrom 1 to 19. In particular embodiments, x is an integer from 1 to 10,and in other embodiments from 1 to 6. It is believed that molecules ofthe Formula II are obtained when, for example, butyl lithium is reactedwith vinyl diphenyl phosphine.

With respect to Formula II, where R⁶ is a substituent according toFormula III, it is believed that the alpha carbon of Formula III (i.e.,the carbon next to the phosphorus atom) will be bonded to the metal atom(i.e., M) of Formula II, and the beta carbon of Formula III (i.e., thesecond carbon atom from the phosphorus atom) will be bonded to the alphacarbon of Formula II.

Again, without wishing to be bound by any particular theory, it isbelieved that certain substituted vinyl organophosphines, such asdihydrocarbyl(2-dihydrocarbylvinyl)phosphines, react to formphosphorus-containing organolithium compounds that can be defined by theformula IV:

where M is a metal, R¹ and R² are each independently monovalent organicgroups, or where R¹ and R² join to form a divalent organic group, whereR³, R⁴, and R⁵ are each independently hydrogen or monovalent organicgroups, or where R³ and R⁴ join to form a divalent organic group, andwhere R⁶ is a bond or a divalent organic group. In particularembodiments, R³, R⁴, and R⁵ are hydrocarbyl groups. In these or otherparticular embodiments, M is a group I (e.g. lithium) or group II (e.g.magnesium) metal.

In these or other particular embodiments, R⁶ may be a divalent organicgroup defined by the Formula III. With respect to Formula IV, where R⁶is a substituent according to Formula III, it is believed that the betacarbon of Formula III will be bonded to the metal atom of Formula IV,and the alpha carbon of Formula III will be bonded to the beta carbon ofFormula IV.

In one or more embodiments, stabilized solutions of thephosphorus-containing organometal initiator of this invention can beprepared by chain extending the initiator compound. The technique ofchain extending anionic polymerization initiators is known in the art asdescribed in U.S. Publication No. 2011/0112263 and U.S. ProvisionalApplication Ser. No. 61/576,043, which are incorporated herein byreference. In general, this technique includes polymerizing a limitedamount of monomer (e.g., 3 to 25 units of butadiene) to form astabilized chain-extended initiator. These chain-extended initiators canbe represented by the formulas II and IV above, where R⁶ includes adivalent oligomeric substituent formed by the polymerization of thelimited amount of monomer (i.e., 3 to 25 mer units).

Polymerization Process

In one or more embodiments, polydiene or polydiene copolymers areprepared by introducing the pre-formed phosphorus-containing organometalcompound with monomer to be polymerized. It is believed that thepolymerization proceeds by anionic polymerization of the monomer withthe phosphorus-containing organometal compound serving as the initiator.As will be described in more detail below, the polymer, which includes aphosphorus-containing functional group at the head of the polymer chain,may be end-functionalized to produce a polymer having a functional groupat the tail-end of the polymer (i.e., a telechelic polymer is produced).

In one or more embodiments, the monomer to be polymerized includesconjugated diene monomer and optionally monomer copolymerizabletherewith. Examples of conjugated diene monomer include 1,3-butadiene,isoprene, 1,3-pentadiene, 1,3-hexadiene, 2,3-dimethyl-1,3-butadiene,2-ethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene,4-methyl-1,3-pentadiene, and 2,4-hexadiene. Mixtures of two or moreconjugated dienes may also be utilized in copolymerization. Examples ofmonomer copolymerizable with conjugated diene monomer may includevinyl-substituted aromatic compounds such as styrene, p-methylstyrene,α-methylstyrene, and vinyl naphthalene.

In one or more embodiments, the anionically-polymerized polymers areprepared by anionic polymerization, wherein monomer is polymerized byusing an anionic initiator. The key mechanistic features of anionicpolymerization have been described in books (e.g., Hsieh, H. L.; Quirk,R. P. Anionic Polymerization: Principles and Practical Applications;Marcel Dekker: New York, 1996) and review articles (e.g.,Hadjichristidis, N.; Pitsikalis, M.; Pispas, S.; Iatrou, H.; Chem. Rev.2001, 101(12), 3747-3792). Anionic initiators may advantageously producereactive polymers (e.g. living polymers) that, prior to quenching, arecapable of reacting with additional monomers for further chain growth orreacting with certain functionalizing agents to give functionalizedpolymers. As those skilled in the art appreciate, these reactivepolymers include a reactive chain end, which is believed to be ionic, atwhich a reaction between the functionalizing agent and the polymer takesplace.

Anionic polymerization may be conducted in polar solvents, non-polarsolvents, and mixtures thereof. In one or more embodiments, a solventmay be employed as a carrier to either dissolve or suspend the initiatorin order to facilitate the delivery of the initiator to thepolymerization system. Solvents useful for conducting thepolymerizations include those solvents mentioned above that are usefulin preparing the initiator solutions. In particular embodiments, alkanesand/or cycloalkanes are employed.

When preparing elastomeric copolymers, such as those containingconjugated diene monomers and vinyl-substituted aromatic monomers, theconjugated diene monomers and vinyl-substituted aromatic monomers may beused at a ratio of 95:5 to 50:50, or in other embodiments, 95:5 to65:35. In order to promote the randomization of comonomers incopolymerization and to control the microstructure (such as 1,2-linkageof conjugated diene monomer) of the polymer, a randomizer, which istypically a polar coordinator, may be employed along with the anionicinitiator. Compounds useful as randomizers include those polarcoordinators mentioned above. In other embodiments, useful randomizersinclude potassium alkoxides.

The amount of randomizer to be employed may depend on various factorssuch as the desired microstructure of the polymer, the ratio of monomerto comonomer, the polymerization temperature, as well as the nature ofthe specific randomizer employed. In one or more embodiments, the amountof randomizer employed may range between 0.05 and 100 moles per mole ofthe anionic initiator. In one or more embodiments, the amount ofrandomizer employed includes that amount introduced during formation ofthe initiator (i.e., the lithium organophosphide). In other embodiments,additional randomizer is added to the monomer to be polymerized.

The anionic initiator and the randomizer can be introduced to thepolymerization system by various methods. In one or more embodiments,the anionic initiator and the randomizer may be added separately to themonomer to be polymerized in either a stepwise or simultaneous manner.In other embodiments, the anionic initiator and the randomizer may bepre-mixed outside the polymerization system either in the absence of anymonomer or in the presence of a small amount of monomer, and theresulting mixture may be aged, if desired, and then added to the monomerthat is to be polymerized.

Production of the reactive polymer can be accomplished by polymerizingconjugated diene monomer, optionally together with monomercopolymerizable with conjugated diene monomer, in the presence of aneffective amount of the initiator. The introduction of the initiator,the conjugated diene monomer, optionally the comonomer, and any solventif employed forms a polymerization mixture in which the reactive polymeris formed. The amount of the initiator to be employed may depend on theinterplay of various factors such as the type of initiator employed, thepurity of the ingredients, the polymerization temperature, thepolymerization rate and conversion desired, the molecular weightdesired, and many other factors.

In one or more embodiments, the initiator loading (i.e., the amount ofphosphorus-containing organolithium compound) may be varied from about0.05 to about 100 mmol, in other embodiments from about 0.1 to about 50mmol, and in still other embodiments from about 0.2 to about 5 mmol per100 gram of monomer.

In one or more embodiments, the polymerization may be carried out in apolymerization system that includes a substantial amount of solvent. Inone embodiment, a solution polymerization system may be employed inwhich both the monomer to be polymerized and the polymer formed aresoluble in the solvent. In another embodiment, a precipitationpolymerization system may be employed by choosing a solvent in which thepolymer formed is insoluble. In both cases, an amount of solvent inaddition to the amount of solvent that may be used in preparing thecatalyst is usually added to the polymerization system. The additionalsolvent may be the same as or different from the solvent used inpreparing the catalyst or initiator. Exemplary solvents have been setforth above. In one or more embodiments, the solvent content of thepolymerization mixture may be more than 20% by weight, in otherembodiments more than 50% by weight, and in still other embodiments morethan 80% by weight based on the total weight of the polymerizationmixture.

The polymerization may be conducted in any conventional polymerizationvessels known in the art. In one or more embodiments, solutionpolymerization can be conducted in a conventional stirred-tank reactor.

In one or more embodiments, all of the ingredients used for thepolymerization can be combined within a single vessel (e.g., aconventional stirred-tank reactor), and all steps of the polymerizationprocess can be conducted within this vessel. In other embodiments, twoor more of the ingredients can be pre-combined in one vessel and thentransferred to another vessel where the polymerization of monomer (or atleast a major portion thereof) may be conducted.

The polymerization can be carried out as a batch process, a continuousprocess, or a semi-continuous process. In the semi-continuous process,the monomer is intermittently charged as needed to replace that monomeralready polymerized. In one or more embodiments, the conditions underwhich the polymerization proceeds may be controlled to maintain thetemperature of the polymerization mixture within a range from about −10°C. to about 200° C., in other embodiments from about 0° C. to about 150°C., and in other embodiments from about 20° C. to about 100° C. In oneor more embodiments, the heat of polymerization may be removed byexternal cooling by a thermally controlled reactor jacket, internalcooling by evaporation and condensation of the monomer through the useof a reflux condenser connected to the reactor, or a combination of thetwo methods. Also, conditions may be controlled to conduct thepolymerization under a pressure of from about 0.1 atmospheres to about50 atmospheres, in other embodiments from about 0.5 atmospheres to about20 atmospheres, and in other embodiments from about 1 atmosphere toabout 10 atmospheres. In one or more embodiments, the pressures at whichthe polymerization may be carried out include those that ensure that themajority of the monomer is in the liquid phase. In these or otherembodiments, the polymerization mixture may be maintained underanaerobic conditions.

Functionalization

In any event, this reaction produces a reactive polymer having areactive or living end. In one or more embodiments, at least about 30%of the polymer molecules contain living ends, in other embodiments atleast about 50% of the polymer molecules contain living ends, and inother embodiments at least about 80% contain living ends.

The living polymer can be protonated or subsequently functionalized orcoupled. Protonation can occur by the addition of any compound that candonate a proton to the living end. Examples include water, isopropylalcohol, and methyl alcohol.

In one or more embodiments, the living polymer can be terminated with acompound that will impart a functional group to the terminus of thepolymer. Useful functionalizing agents include those conventionallyemployed in the art. Types of compounds that have been used toend-functionalize living polymers include carbon dioxide, benzophenones,benzaldehydes, imidazolidones, pyrrolidinones, carbodiimides, ureas,isocyanates, and Schiff bases including those disclosed in U.S. Pat.Nos. 3,109,871, 3,135,716, 5,332,810, 5,109,907, 5,210,145, 5,227,431,5,329,005, 5,935,893, which are incorporated herein by reference.Specific examples include trialkyltin halides such as triisobutyltinchloride, as disclosed in U.S. Pat. Nos. 4,519,431, 4,540,744,4,603,722, 5,248,722, 5,349,024, 5,502,129, and 5,877,336, which areincorporated herein by reference. Other examples include cyclic aminocompounds such as hexamethyleneimine alkyl chloride, as disclosed inU.S. Pat. Nos. 5,786,441, 5,916,976 and 5,552,473, which areincorporated herein by reference. Other examples include N-substitutedaminoketones, N-substituted thioaminoketones, N-substitutedaminoaldehydes, and N-substituted thioaminoaldehydes, includingN-methyl-2-pyrrolidone or dimethylimidazolidinone (i.e.,1,3-dimethylethyleneurea) as disclosed in U.S. Pat. Nos. 4,677,165,5,219,942, 5,902,856, 4,616,069, 4,929,679, 5,115,035, and 6,359,167,which are incorporated herein by reference. Additional examples includecyclic sulfur-containing or oxygen containing azaheterocycles such asdisclosed in WO 2004/020475, U.S. Publication No. 2006/0178467 and U.S.Pat. No. 6,596,798, which are incorporated herein by reference. Otherexamples include boron-containing terminators such as disclosed in U.S.Pat. No. 7,598,322, which is incorporated herein by reference. Stillother examples include cyclic siloxanes such ashexamethylcyclotrisiloxane, including those disclosed in co-pending U.S.Ser. No. 60/622,188, which is incorporated herein by reference. Further,other examples include α-halo-ω-amino alkanes, such as1-(3-bromopropyl)-2,2,5,5-tetramethyl-1-aza-2,5-disilacyclopentane,including those disclosed in co-pending U.S. Ser. Nos. 60/624,347 and60/643,653, which are incorporated herein by reference. Yet otherexamples include silane-type terminators, such as3-(1,3-dimethylbutylidene)aminopropyl-triethoxysilane. Still otherexamples include benzaldehyde-type terminators, such as3,4-di(tert-butyldimethylsiloxy)benzaldehyde, which are disclosed inU.S. Publication No. 2010/0286348, which is incorporated herein byreference.

In one or more embodiments, the living polymer can be coupled to linktwo or more living polymer chains together. In certain embodiments, theliving polymer can be treated with both coupling and functionalizingagents, which serve to couple some chains and functionalize otherchains. The combination of coupling agent and functionalizing agent canbe used at various molar ratios. Although the terms coupling andfunctionalizing agents have been employed in this specification, thoseskilled in the art appreciate that certain compounds may serve bothfunctions. That is, certain compounds may both couple and provide thepolymer chains with a functional group. Those skilled in the art alsoappreciate that the ability to couple polymer chains may depend upon theamount of coupling agent reacted with the polymer chains. For example,advantageous coupling may be achieved where the coupling agent is addedin a one to one ratio between the equivalents of lithium on theinitiator and equivalents of leaving groups (e.g., halogen atoms) on thecoupling agent.

Exemplary coupling agents include metal halides, metalloid halides,alkoxysilanes, and alkoxystannanes.

In one or more embodiments, useful metal halides or metalloid halidesmay be selected from the group comprising compounds expressed by theformula (1) R¹ _(n)M¹X_(4-n), the formula (2) M¹X₄, and the formula (3)M²X₃, where R¹ is the same or different and represents a monovalentorganic group with carbon number of 1 to about 20, M¹ in the formulas(1) and (2) represents a tin atom, silicon atom, or germanium atom, M²represents a phosphorus atom, X represents a halogen atom, and nrepresents an integer of 0-3.

Exemplary compounds expressed by the formula (1) include halogenatedorganic metal compounds, and the compounds expressed by the formulas (2)and (3) include halogenated metal compounds.

In the case where M¹ represents a tin atom, the compounds expressed bythe formula (1) can be, for example, triphenyltin chloride, tributyltinchloride, triisopropyltin chloride, trihexyltin chloride, trioctyltinchloride, diphenyltin dichloride, dibutyltin dichloride, dihexyltindichloride, dioctyltin dichloride, phenyltin trichloride, butyltintrichloride, octyltin trichloride and the like. Furthermore, tintetrachloride, tin tetrabromide and the like can be exemplified as thecompounds expressed by formula (2).

In the case where M¹ represents a silicon atom, the compounds expressedby the formula (1) can be, for example, triphenylchlorosilane,trihexylchlorosilane, trio ctylchlorosilane, tributylchlorosilane,trimethylchlorosilane, diphenyldichlorosilane, dihexyldichlorosilane,dioctyldichlorosilane, dibutyldichlorosilane, dimethyldichlorosilane,methyltrichlorosilane, phenyltrichlorosilane, hexyltrichlorosilane,octyltrichlorosilane, butyltrichlorosilane, methyltrichlorosilane andthe like. Furthermore, silicon tetrachloride, silicon tetrabromide andthe like can be exemplified as the compounds expressed by the formula(2). In the case where M¹ represents a germanium atom, the compoundsexpressed by the formula (1) can be, for example, triphenylgermaniumchloride, dibutylgermanium dichloride, diphenylgermanium dichloride,butylgermanium trichloride and the like. Furthermore, germaniumtetrachloride, germanium tetrabromide and the like can be exemplified asthe compounds expressed by the formula (2). Phosphorus trichloride,phosphorus tribromide and the like can be exemplified as the compoundsexpressed by the formula (3). In one or more embodiments, mixtures ofmetal halides and/or metalloid halides can be used.

In one or more embodiments, useful alkoxysilanes or alkoxystannanes maybe selected from the group comprising compounds expressed by the formula(1) R¹ _(n)M¹(OR)_(4-n), where R¹ is the same or different andrepresents a monovalent organic group with carbon number of 1 to about20, M¹ represents a tin atom, silicon atom, or germanium atom, ORrepresents an alkoxy group where R represents a monovalent organicgroup, and n represents an integer of 0-3.

Exemplary compounds expressed by the formula (4) include tetraethylorthosilicate, tetramethyl orthosilicate, tetrapropyl orthosilicate,tetraethoxy tin, tetramethoxy tin, and tetrapropoxy tin.

In one embodiment, the functionalizing agent may be added to the livingpolymer cement (i.e., polymer and solvent) once a peak polymerizationtemperature, which is indicative of nearly complete monomer conversion,is observed. Because live ends may self-terminate, the functionalizingagent should be added within about 25 to 35 minutes of the peakpolymerization temperature.

In one or more embodiments, the amount of the functionalizing agentemployed can be described with reference to the amount of metal cationassociated with the initiator. For example, the molar ratio of thefunctionalizing agent to the lithium metal may be from about 0.1:1 toabout 2:1, in other embodiments from about 0.3:1 to about 2:1, in otherembodiments from about 0.6:1 to about 1.5:1, and in other embodimentsfrom 0.8:1 to about 1.2:1.

In one or more embodiments, the functionalizing agent may be introducedto the polymerization mixture as a solution within an organic solvent.Suitable solvents include those described herein including those used toprepare the polymerization mixture. In certain embodiments, the samesolvent employed to prepare the polymerization mixture can be used toprepare the solution of the functionalizing agent. Advantageously, oneor more functionalizing agent of the present invention formtechnologically useful and stable solutions in aliphatic solvents suchas hexane, cyclohexane, and/or derivatives thereof. In one or moreembodiments, the concentration of the functionalizing agent in aliphaticsolvent may be at least 0.05 molar, in other embodiments at least 0.5molar, in other embodiments at least 1 molar and in other embodimentsfrom about 0.5 to about 3 molar.

In one or more embodiments, the functionalizing agent can be reactedwith the reactive polymer after a desired monomer conversion is achievedbut before the polymerization mixture is quenched by a quenching agent.In one or more embodiments, the reaction between the functionalizingagent and the reactive polymer may take place within 180 minutes, inother embodiments within 60 minutes, in other embodiments within 30minutes, in other embodiments within 5 minutes, and in other embodimentswithin one minute after the peak polymerization temperature is reached.In one or more embodiments, the reaction between the functionalizingagent and the reactive polymer can occur once the peak polymerizationtemperature is reached. In other embodiments, the reaction between thefunctionalizing agent and the reactive polymer can occur after thereactive polymer has been stored. In one or more embodiments, thestorage of the reactive polymer occurs at room temperature or belowunder an inert atmosphere. In one or more embodiments, the reactionbetween the functionalizing agent and the reactive polymer may takeplace at a temperature from about 10° C. to about 150° C., and in otherembodiments from about 20° C. to about 100° C. The time required forcompleting the reaction between the functionalizing agent and thereactive polymer depends on various factors such as the type and amountof the catalyst or initiator used to prepare the reactive polymer, thetype and amount of the functionalizing agent, as well as the temperatureat which the functionalization reaction is conducted. In one or moreembodiments, the reaction between the functionalizing agent and thereactive polymer can be conducted for about 10 to 60 minutes.

The amount of the functionalizing agent that can be reacted with thereactive polymer may depend on various factors including the type andamount of catalyst or initiator used to initiate the polymerization andthe desired degree of functionalization. In one or more embodiments, theamount of the functionalizing agent employed can be described withreference to the amount of metal cation associated with the initiator.For example, the molar ratio of the functionalizing agent to the lithiummetal may be from about 0.1:1 to about 2:1, in other embodiments fromabout 0.3:1 to about 2:1, in other embodiments from about 0.6:1 to about1.5:1, and in other embodiments from 0.8:1 to about 1.2:1.

In one or more embodiments, the functionalizing agent may be introducedto the polymerization mixture as a solution within an organic solvent.Suitable solvents include those described herein including those used toprepare the polymerization mixture. In certain embodiments, the samesolvent employed to prepare the polymerization mixture can be used toprepare the solution of the functionalizing agent. Advantageously, oneor more functionalizing agent of the present invention formtechnologically useful and stable solutions in aliphatic solvents suchas hexane, cyclohexane, and/or derivatives thereof. In one or moreembodiments, the concentration of the functionalizing agent in aliphaticsolvent may be at least 0.05 molar, in other embodiments at least 0.5molar, in other embodiments at least 1 molar and in other embodimentsfrom about 0.5 to about 3 molar.

Quenching

In one or more embodiments, in lieu of or after the reaction between thereactive polymer and the functionalizing agent has been accomplished orcompleted, a quenching agent can be added to the polymerization mixturein order to inactivate any residual reactive polymer chains and/or theinitiator. The quenching agent may include a protic compound, whichincludes, but is not limited to, an alcohol, a carboxylic acid, aninorganic acid, water, or a mixture thereof. An antioxidant such as2,6-di-tert-butyl-4-methylphenol may be added along with, before, orafter the addition of the quenching agent. The amount of the antioxidantemployed may be in the range of 0.2% to 1% by weight of the polymerproduct.

Polymer Isolation

When the polymerization mixture has been quenched, the polymer productcan be recovered from the polymerization mixture by using anyconventional procedures of desolventization and drying that are known inthe art. For instance, the polymer can be recovered by subjecting thepolymer cement to steam desolventization, followed by drying theresulting polymer crumbs in a hot air tunnel. Alternatively, the polymermay be recovered by directly drying the polymer cement on a drum dryer.The content of the volatile substances in the dried polymer can be below1%, and in other embodiments below 0.5% by weight of the polymer.

Polymer Product

While the use of the phosphorus-containing initiator, optionally with acoupling agent and/or functionalizing agent, are believed to react toproduce novel functionalized polymers, the exact chemical structure ofthe functionalized polymer produced in every embodiment is not knownwith any great degree of certainty, particularly as the structurerelates to the residue imparted to the polymer chain end by thefunctionalizing agent. Indeed, it is speculated that the structure ofthe functionalized polymer may depend upon various factors such as theconditions employed to prepare the reactive polymer (e.g., the type andamount of the initiator) and the conditions employed to react thefunctionalizing agent with the reactive polymer.

In one or more embodiments, practice of the present inventionadvantageously produces polymer having a relatively high percentage ofphosphorus-containing groups located at the head of the polymer chain.Thus, while the prior art contemplates the use of lithium dialkylphosphides as initiators, practice of the present inventionadvantageously yields an unexpectedly higher number of polymer chainshaving a phosphorus-containing head group. Moreover, this isadvantageously achieved at technologically useful polymerizationconditions and rates, which generally include temperatures in excess of25° C., in other embodiments in excess of 30° C., and in otherembodiments in excess of 50° C. In one or more embodiments, the polymerproduced according to the present invention includes at least 30%, inother embodiments at least 50%, and in other embodiments at least 60%polymer having a phosphorus-containing head group.

In one or more embodiments, polymers produced according to embodimentsof the present invention may include a functionalized polymer defined bythe formula V:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, where R⁶ is abond or a divalent organic group, P is a phosphorus atom, π is a polymerchain, and ω is a hydrogen atom, a terminal functional group, or amultivalent coupling group. In the case where ω is a coupling group, wmay have a functionality of 2 or more (e.g., 3 or 4) whereby 2 or morepolymer chains (i.e., π) extend from the coupling group.

In other embodiments, polymers produced according to the presentinvention may include a functionalized polymer defined by the formulaVI:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, where R⁶ is abond or a divalent organic group, P is a phosphorus atom, π is a polymerchain, and ω is a hydrogen atom, a terminal functional group, or amultivalent coupling group. In the case where ω is a coupling group, ωmay have a functionality of 2 or more (e.g., 3 or 4) whereby 2 or morepolymer chains (i.e., π) extend from the coupling group.

In one or more embodiments, the polymer chain (π) of the functionalizedpolymer contains unsaturation. In these or other embodiments, thepolymer chain is vulcanizable. The polymer chain can have a glasstransition temperature (T_(g)) that is less than 0° C., in otherembodiments less than −20° C., and in other embodiments less than −30°C. In one embodiment, the polymer chain may exhibit a single glasstransition temperature.

In one or more embodiments, the polymer chain (π) prepared according tothis invention may be medium or low cis polydienes (or polydienecopolymers) including those prepared by anionic polymerizationtechniques. These polydienes can have a cis content of from about 10% to60%, in other embodiments from about 15% to 55%, and in otherembodiments from about 20% to about 50%, where the percentages are basedupon the number of diene mer units in the cis configuration versus thetotal number of diene mer units. These polydienes may also have a1,2-linkage content (i.e. vinyl content) from about 10% to about 90%, inother embodiments from about 10% to about 60%, in other embodiments fromabout 15% to about 50%, and in other embodiments from about 20% to about45%, where the percentages are based upon the number of diene mer unitsin the vinyl configuration versus the total number of diene mer units.The balance of the diene units may be in the trans-1,4-linkageconfiguration.

In particular embodiments, the polymer chain (π) may be a copolymer ofbutadiene, styrene, and optionally isoprene. These may include randomcopolymers. In other embodiments, the polymers are block copolymers ofpolybutadiene, polystyrene, and optionally polyisoprene. In particularembodiments, the polymers are hydrogenated or partially hydrogenated. Inone or more embodiments, the polymer chain (π) is a copolymer of styreneand conjugated diene where the molar ratio of styrene mer units toconjugated diene mer units is from about 1:1 to about 0.05:1, in otherembodiments from about 0.7:1 to about 0.1:1, and in other embodimentsfrom about 0.5:1 to about 0.2:1.

In one or more embodiments, the polymer chain π is ananionically-polymerized polymer selected from the group consisting ofpolybutadiene, polyisoprene, poly(styrene-co-butadiene),poly(styrene-co-butadiene-co-isoprene), poly(isoprene-co-styrene), andpoly(butadiene-co-isoprene). The number average molecular weight (M_(n))of these polymers may be from about 1,000 to about 1,000,000, in otherembodiments from about 5,000 to about 1,000,000, in other embodimentsfrom about 50,000 to about 500,000, and in other embodiments from about100,000 to about 300,000, as determined by using gel permeationchromatography (GPC) calibrated with polystyrene standards andMark-Houwink constants for the polymer in question. The polydispersity(M_(w)/M_(n)) of these polymers may be from about 1.0 to about 3.0, andin other embodiments from about 1.1 to about 2.0.

In particular embodiments, the polymers of this invention are copolymersof 1,3-butadiene, styrene, and optionally isoprene. These may includerandom copolymers and block copolymers. In one or more embodiments, therandom polydiene copolymers may include from about 10 to about 50% byweight, in other embodiments from about 15 to about 40% by weight, andin other embodiments from about 20 to about 30% by weight units derivingfrom styrene, with the balance including units deriving from conjugateddiene monomer, such as 1,3-butadiene, having low or medium cis contentas described above.

In particular embodiments, the functional group located at the chain end(i.e., ω) can react or interact with reinforcing filler to reduce the50° C. hysteresis loss of vulcanizates prepared there from.

Use in Tires

The functionalized polymers of this invention are particularly useful inpreparing tire components. In particular embodiments, these tirecomponents include silica filler. These tire components can be preparedby using the functionalized polymers alone or together with otherrubbery polymers (i.e., polymers that can be vulcanized to formcompositions possessing elastomeric properties). Other rubbery polymersthat may be used include natural and synthetic elastomers. The syntheticelastomers typically derive from the polymerization of conjugated dienemonomers. These conjugated diene monomers may be copolymerized withother monomers such as vinyl-substituted aromatic monomers. Otherrubbery polymers may derive from the polymerization of ethylene togetherwith one or more α-olefins and optionally one or more diene monomers.

Useful rubbery polymers include natural rubber, synthetic polyisoprene,polybutadiene, polyisobutylene-co-isoprene, neoprene,poly(ethylene-co-propylene), poly(styrene-co-butadiene),poly(styrene-co-isoprene), and poly(styrene-co-isoprene-co-butadiene),poly(isoprene-co-butadiene), poly(ethyl ene-co-propylene-co-diene),polysulfide rubber, acrylic rubber, urethane rubber, silicone rubber,epichlorohydrin rubber, and mixtures thereof. These elastomers can havea myriad of macromolecular structures including linear, branched andstar shaped. Other ingredients that are typically employed in rubbercompounding may also be added.

The rubber compositions may include fillers such as inorganic andorganic fillers. The organic fillers include carbon black and starch.The inorganic fillers may include silica, aluminum hydroxide, magnesiumhydroxide, clays (hydrated aluminum silicates), and mixtures thereof.

A multitude of rubber curing agents (also called vulcanizing agents) maybe employed, including sulfur or peroxide-based curing systems. Curingagents are described in Kirk-Othmer, ENCYCLOPEDIA OF CHEMICALTECHNOLOGY, Vol. 20, pgs. 365-468, (3^(rd) Ed. 1982), particularlyVulcanization Agents and Auxiliary Materials, pgs. 390-402, and A. Y.Coran, Vulcanization, ENCYCLOPEDIA OF POLYMER SCIENCE AND ENGINEERING,(2^(nd) Ed. 1989), which are incorporated herein by reference.Vulcanizing agents may be used alone or in combination.

Other ingredients that may be employed include accelerators, oils,waxes, scorch inhibiting agents, processing aids, zinc oxide, tackifyingresins, reinforcing resins, fatty acids such as stearic acid, peptizers,and one or more additional rubbers.

These rubber compositions are useful for forming tire components such astreads, subtreads, black sidewalls, body ply skins, bead filler, and thelike. Preferably, the functional polymers are employed in tread andsidewall formulations. In one or more embodiments, these treadformulations may include from about 10% to about 100% by weight, inother embodiments from about 35% to about 90% by weight, and in otherembodiments from about 50% to 80% by weight of the functionalizedpolymer based on the total weight of the rubber within the formulation.

In one or more embodiments, the vulcanizable rubber composition may beprepared by forming an initial masterbatch that includes the rubbercomponent and filler (the rubber component optionally including thefunctionalized polymer of this invention). This initial masterbatch maybe mixed at a starting temperature of from about 25° C. to about 125° C.with a discharge temperature of about 135° C. to about 180° C. Toprevent premature vulcanization (also known as scorch), this initialmasterbatch may exclude vulcanizing agents. Once the initial masterbatchis processed, the vulcanizing agents may be introduced and blended intothe initial masterbatch at low temperatures in a final mixing stage,which preferably does not initiate the vulcanization process. Forexample, the vulcanizing agents may be introduced at a temperature lessthan 140° C., in other embodiments less than 120° C., and in otherembodiments less than 110° C. Optionally, additional mixing stages,sometimes called remills, can be employed between the masterbatch mixingstage and the final mixing stage. Various ingredients including thefunctionalized polymer of this invention can be added during theseremills. Rubber compounding techniques and the additives employedtherein are generally known as disclosed in The Compounding andVulcanization of Rubber, in Rubber Technology (2^(nd) Ed. 1973).

In order to demonstrate the practice of the present invention, thefollowing examples have been prepared and tested. The examples shouldnot, however, be viewed as limiting the scope of the invention. Theclaims will serve to define the invention.

EXAMPLES Sample 1 Control Non-Functional Polymer

To a 7.57 L stainless steel reactor equipped with turbine agitatorblades was added 1.55 kg hexanes, 0.39 kg 35.0 wt % styrene in hexanes,and 2.50 kg 21.8 wt % 1,3-butadiene in hexanes. To the reactor wascharged 3.44 mL of 1.65 M n-butyl lithium in hexanes, 2.06 mL of 1.60 M2,2-ditetrahydrofurylpropane (DTHFP) in hexanes and the batch was heatedto an exotherm of 87° C. Approximately 30 minutes after exotherm, aportion of the contents were discharged into isopropanol containingantioxidant (BHT). The polymer was drum dried to yield a polymer withproperties listed in Table 1.

Sample 2 Synthesis of SBR Initiated with the Butyl Lithium Adduct toVinyldiphenylphosphine

To a 7.57 L stainless steel reactor equipped with turbine agitatorblades was added 1.55 kg hexanes, 0.39 kg 35.0 wt % styrene in hexanes,and 2.50 kg 21.8 wt % 1,3-butadiene in hexanes. To the reactor wascharged a premixed solution (which is bright yellow in color) of 3.44 mLof 1.65 M n-butyl lithium in hexanes, 4.36 mL of 1.17 Mvinyldiphenylphosphine in hexanes, and 2.06 mL of 1.60 M2,2-ditetrahydrofurylpropane (DTHFP) in hexanes and the batch was heatedto an exotherm of 88.3° C. Approximately 135 minutes after exotherm,part of the contents were discharged into isopropanol containingantioxidant (BHT). The polymer was drum dried to yield a polymer withproperties listed in Table 1.

Sample 3 Synthesis of SBR Initiated with the Butyl Lithium Adduct toVinyldiphenylphosphine and Terminated with Chlorodiphenylphosphine

A portion of the contents from the polymerization in Sample 2 weredischarged into nitrogen purged bottles and terminated with 1 equivalentof chlorodiphenylphosphine/BuLi. The polymer was coagulated inisopropanol containing antioxidant and drum dried to yield a polymerwith properties listed in Table 1.

Sample 4 Synthesis of SBR Initiated with the Butyl Lithium Adduct to 2Equivalents of Vinyldiphenylphosphine

To a 7.57 L stainless steel reactor equipped with turbine agitatorblades was added 1.50 kg hexanes, 0.39 kg 35.0 wt % styrene in hexanes,and 2.56 kg 21.3 wt % 1,3-butadiene in hexanes. To the reactor wascharged a premixed solution (which is bright yellow in color) of 3.44 mLof 1.65 M n-butyl lithium in hexanes, 9.69 mL of 1.17 Mvinyldiphenylphosphine in hexanes, and 3.54 mL of 1.60 M2,2-ditetrahydrofurylpropane (DTHFP) in hexanes and the batch was heatedto an exotherm of 84.4° C. Approximately 30 minutes after exotherm, partof the contents were discharged into isopropanol containing antioxidant(BHT). The polymer was drum dried to yield a polymer with propertieslisted in Table 1.

TABLE 1 Analytical Properties of Polymers M_(n) M_(w) T_(g), Styrene, %Vinyl Phosphorus % Sample (kg/mol) (kg/mol) ° C. wt % (BD = 100%) (ppm)Functionality 1 117.1 123.4 −36.0 20.6 54.6 2 0.7 2 121.3 133.7 −32.922.5 51.7 196 76.9 3 117.6 128.4 −32.9 22.5 51.7 408 77.4 4 128.5 200.5−30.2 21.4 58.0 348 69.3

M_(n) and M_(w) were measured using GPC with polystyrene standards.T_(g) was measured using DSC. Styrene weight percent and vinyl contentwere determined using proton NMR. Phosphorus content was determined byusing ICP (inductively coupled plasma); the reported functionality wascalculated by ppm phosphorus found divided by theoretical ppm phosphorustimes 100%. Theoretical phosphorus was calculated based upon phosphorusatoms in the polymer multiplied by phosphorus molecular weight dividedby M_(n) times 1,000,000.

Compounds 1A-3A. Compounding of Polymers in all Carbon Black Formulation

The formulations of the compound mixtures are presented in Table 2 inweight parts. Each rubber compound was prepared in two portions namedinitial (masterbatch) and final. In the initial part, the polymer fromSample 1-3 was mixed with carbon black, an antioxidant, stearic acid,wax, aromatic oil, and zinc oxide.

TABLE 2 Ingredients Masterbatch Synthetic 100 Polymer Carbon Black 55Wax 1 Antioxidant 0.95 Zinc Oxide 2.5 Stearic Acid 2 Aromatic Oil 10Total 171.45 Final Sulfur 1.3 Accelerators 1.9 Total 174.65

The initial portion of the compound was mixed in a 65 g Banbury mixeroperating at 60 RPM and 133° C. First, polymer was placed in the mixer,and after 0.5 minutes, the remaining ingredients except the stearic acidwere added. The stearic acid was then added after 3 minutes. Theinitials were mixed for 5-6 minutes. At the end of mixing thetemperature was approximately 165° C. The sample was transferred to amill operating at a temperature of 60° C., where it was sheeted andsubsequently cooled to room temperature.

The finals were mixed by adding the initials and the curative materialsto the mixer simultaneously. The initial mixer temperature was 65° C.and it was operating at 60 RPM. The final material was removed from themixer after 2.25 minutes when the material temperature was between100-105° C. The finals were sheeted into Dynastat buttons and15.2×15.2×0.19 cm sheets. The samples were cured at 171° C. for 15minutes in standard molds placed in a hot press. The results of thevarious tests performed are reported in Table 3. Testing was conductedin a manner similar to that reported above.

TABLE 3 Physical Properties of Compounded Stocks Compound CompoundCompound Property 1A (Control) 2A 3A ML₁₊₄(130° C.) 20.2 25.7 26.7 200%Modulus @23° C. (MPa) 8.25 8.35 8.13 T_(b) @23° C. (MPa) 15.8 14.9 12.60E_(b) @23° C. (%) 335 314 276 tan δ 5% γ, 50° C. 0.224 0.194 0.180 ΔG’(50° C.) (MPa) 3.420 2.360 1.800 tan δ 0.5% γ, 0° C. 0.398 0.399 0.406

The Mooney viscosities (ML₁₊₄) of the polymer samples were determined at100° C. by using a Monsanto Mooney viscometer with a large rotor, aone-minute warm-up time, and a four-minute running time.

The tensile mechanical properties were measured using the standardprocedure described in the ASTM-D 412 at 25° C. and 100° C. The tensiletest specimens had dumbbell shapes with a thickness of 1.9 mm. Aspecific gauge length of 25.4 mm is used for the tensile test.

Temperature sweep experiments were conducted with a frequency of 10 Hzusing 0.5% strain for temperature ranging from −100° C. to −10° C., and2% strain for the temperature ranging from −10° C. to 100° C. G′ is thestorage modulus measured at 10 Hz and 5% strain at 50° C. Payne Effect(ΔG′) was estimated from the change in G′ obtained from the strain sweepanalysis conducted at a frequency of 1 Hz at 50° C. with strain sweepingfrom 0.25% to 14.00% using a Rheometric Dynamic Analyzer (RDA).

Compounds 1B-4B. Compounding of Polymers in all Silica Formulation

The formulations of the compound mixtures are presented in Table 4 inweight parts. Each rubber compound was prepared in three portions namedinitial (masterbatch), remill and final. In the initial part, thepolymer from Samples 1-4 was mixed with silica, an antioxidant, stearicacid, wax, oil, and zinc oxide.

TABLE 4 Ingredients Masterbatch Synthetic Polymer 80 Natural Rubber 20Silica 52.5 Wax 2 Antioxidant 0.95 Stearic Acid 2 Oil 10 Total 167.45Remill Silica 2.5 Silica Coupling Agent 5 Final Sulfur 1.5 Accelerators4.1 Zinc Oxide 1.5

The initial portion of the compound was mixed in a 65 g Banbury mixeroperating at 50 RPM and 133° C. First, polymer was placed in the mixer,and after 0.5 minutes, the remaining ingredients except the stearic acidwere added. The stearic acid was then added after 3 minutes. Theinitials were mixed for 5-6 minutes. At the end of mixing thetemperature was approximately 165° C. The sample was transferred to amill operating at a temperature of 60° C., where it was sheeted andsubsequently cooled to room temperature.

The remills were mixed by adding the initials and silica and shieldingagent to the mixer simultaneously. The initial mixer temperature was133° C. and it was operating at 50 RPM. The initial material was removedfrom the mixer after 3.5 minutes when the material temperature wasbetween 145° C. and 150° C. The sample was transferred to a milloperating at a temperature of 60° C., where it was sheeted andsubsequently cooled to room temperature.

The finals were mixed by adding the initials and the curative materialsto the mixer simultaneously. The initial mixer temperature was 65° C.and it was operating at 45 RPM. The final material was removed from themixer after 2.5 minutes when the material temperature was between100-105° C. The finals were sheeted into Dynastat buttons and15.2×15.2×0.19 inch sheets. The samples were cured at 171° C. for 15minutes in standard molds placed in a hot press. The results of thevarious tests performed are reported in Table 5. Testing was conductedin a manner similar to that reported above.

TABLE 5 Physical Properties of Compounded Stocks Compound 1B CompoundCompound Compound Property (Control) 2B 3B 4B ML₁₊₄ (130° C.) 15.5 21.623.5 53.3 200% Modulus 7.48 7.99 8.13 9.01 @23° C. (MPa) T_(b) @23° C.(MPa) 12.80 12.10 12.80 12.90 E_(b) @23° C. (%) 308 276 283 259 tan δ 5%γ, 50° C. 0.170 0.139 0.131 0.113 (Strain Sweep) ΔG’ (50° C.) (MPa)4.330 3.460 2.580 1.500 tan δ 0.5% γ, 0° C. 0.331 0.352 0.352 0.418(Temperature Sweep)

Continuous Polymerization of SBR Sample 5 Control Non-Functional Polymer

Polymerization was conducted in a 24.6 liter reactor with a 20 minuteresidence time. The reactor was filled with hexane and the jackettemperature was set at 88° C. The following ingredients were meteredinto the bottom of the reactor: 1) 3.0 kg/hr styrene/hexane blend (31.8%styrene), 2) 24.6 kg/hr butadiene/hexane blend (21.7% butadiene), 3) 8.6kg/hr hexane, 4) 0.39 kg/hr DTHFP/hexane (0.10 M DTHFP), 5) 7.2 cc/hr1,2-butadiene (20%), and 6) 0.35 kg/hr lithium initiator/hexane (0.125 Mlithium). An additional stream of 10.6 kg/hr butadiene/hexane blend(21.7% butadiene) was added at the midpoint of the reactor to minimizeblock styrene formation. Polymer cement was removed at the top of thereactor into a storage vessel. After about 1-1.5 hours of polymerizationtime, steady state was achieved with the top temperature of the reactorat 99° C. and the bottom temperature at 91° C. After another hour ofpolymerization, samples were taken at the top of the reactor,drum-dried, and had the following properties: 31 ML4, 2.0 sec t-80, and99.7% conversion (GC).

Sample 6 SBR Initiated with VDPP

Sample 6 was the same as Sample 5 with a couple of exceptions.Ingredient 4, DTHFP/hexane, was added at 0.37 kg/hr (0.10 M DTHFP). Anadditional ingredient, VDPP/hexane (0.18 kg/hr, 0.2 M VDPP) was mixedwith ingredients 3, 4, 5, and 6 and allowed to mix for about 14 minutesprior to entering the bottom of the reactor. Polymer properties forSample 6 were 33 ML4, 2.3 sec t-80, and 99.7% conversion.

TABLE 6 Analytical Properties of Polymers. M_(n) M_(w) T_(g) Styrene, %Vinyl Sample (kg/mol) (kg/mol) ° C. wt % (BD = 100%) 5 94 215 −56.1 11.741.2 6 93 232 −56.1 11.7 41.2Compounds 5-6. Compounding of Polymers in all Silica Formulation.

The polymer samples prepared above were used to make rubber formulations(i.e., compounds) that were prepared using ingredients and a multi-stagemixing procedure as outlined in Table 4.

The initial portion of the compound was mixed in a 65 g Banbury mixeroperating at 50 RPM and 133° C. First, polymer was placed in the mixer,and after 0.5 minutes, the remaining ingredients except the stearic acidwere added. The stearic acid was then added after 3 minutes. Theinitials were mixed for 5-6 minutes. At the end of mixing thetemperature was approximately 165° C. The sample was transferred to amill operating at a temperature of 60° C., where it was sheeted andsubsequently cooled to room temperature.

The remills were mixed by adding the initials and silica and shieldingagent to the mixer simultaneously. The initial mixer temperature was133° C. and it was operating at 50 RPM. The initial material was removedfrom the mixer after 3.5 minutes when the material temperature wasbetween 145° C. and 150° C. The sample was transferred to a milloperating at a temperature of 60° C., where it was sheeted andsubsequently cooled to room temperature.

The finals were mixed by adding the initials and the curative materialsto the mixer simultaneously. The initial mixer temperature was 65° C.and it was operating at 45 RPM. The final material was removed from themixer after 2.5 minutes when the material temperature was between100-105° C. The finals were sheeted into Dynastat buttons and 6×6×0.075inch sheets. The samples were cured at 171° C. for 15 minutes instandard molds placed in a hot press. The results of the various testsperformed are reported in Table 7. Testing was conducted in a mannersimilar to that reported above.

TABLE 7 Physical Properties of Compounded Stocks. Compound 5 Property(Control) Compound 6 ML₁₊₄ (130° C.) 30.7 35.3 200% Modulus @23° C.(MPa) 7.265 7.342 T_(b) @23° C. (MPa) 11.6 11.6 E_(b) @23° C. (%) 291287.349 tan δ 5% γ, 50° C. (Strain Sweep) 0.1482 0.1419 ΔG’ (50° C.)(MPa) 3.341 3.112 tan δ 0.5% γ, 0° C. 0.2020 0.1950 (TemperatureSweep) * ΔG’ = G’(0.25%γ) − G’(14.0%γ)

Various modifications and alterations that do not depart from the scopeand spirit of this invention will become apparent to those skilled inthe art. This invention is not to be duly limited to the illustrativeembodiments set forth herein.

What is claimed is:
 1. A method for preparing a functionalized polymer,the method comprising: polymerizing conjugated diene monomer, optionallytogether with comonomer, using a phosphorus-containing organometalinitiator, where the phosphorus-containing organometal initiator isdefined by the formula II:

where M is lithium, R¹ and R² are each independently monovalent organicgroups, or where R¹ and R² join to form a divalent organic group, whereR³, R⁴, and R⁵ are each independently hydrogen or monovalent organicgroups, or where R³ and R⁴ join to form a divalent organic group, whereR⁶ is a bond or a divalent organic group and where R⁷ is a monovalentorganic group, or where the phosphorus-containing organolithium compoundis defined by the Formula IV:

where M is lithium, R¹ and R² are each independently monovalent organicgroups, or where R¹ and R² join to form a divalent organic group, whereR³, R⁴, and R⁵ are each independently hydrogen or monovalent organicgroups, or where R³ and R⁴ join to form a divalent organic group, andwhere R⁶ is a bond or a divalent organic group, and where R⁷ is amonovalent organic group.
 2. The method of claim 1, where R³, R⁴, and R⁵are each hydrogen atoms.
 3. The method of claim 1, where at least one ofR³, R⁴, and R⁵ is a hydrocarbyl group.
 4. The method of claim 1, wherethe amount of initiator employed is from 0.05 to about 100 mmol per 100g of monomer.
 5. The method of claim 1, where R⁶ of Formula II orFormula IV is defined by the formula III:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, R³, R⁴, and R⁵are hydrocarbyl groups, and where R¹, R², R³, R⁴, and R⁵ are defined asabove, and x is an integer from 1 to
 19. 6. A method for preparing apolymer, the method comprising: preparing an initiator by reacting avinyl organophosphine with an organometal compound, where the vinylorganophosphine is defined by the formula I:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, and where R³, R⁴,and R⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, and where theorganometal compound is defined by the formula MR⁷ _(n), where M islithium, R⁷ is a monovalent organic group, and n is equivalent to thevalence of the lithium; and polymerizing conjugated diene monomer,optionally together with comonomer, by initiating the polymerization ofthe monomer with the initiator.
 7. The method claim 6, where the vinylorganophosphines is selected from the group consisting ofvinyldihydrocarbyl phosphines,dihydrocarbyl(2,2-dihydrocarbyl-1-hydrocarbylvinyl)phosphines,dihydrocarbyl(2,2-dihydrocarbylvinyl)phosphines,dihydrocarbyl(2-hydrocarbylvinyl)phosphines,dihydrocarbyl(2-hydrocarbyl-1-hydrocarbylvinyl)phosphines, anddihydrocarbyl(1-hydrocarbylvinyl)phosphines.
 8. The method of claim 6,the organometal compound being an organolithium compound, where themolar ratio of organolithium to vinyl organophosphine (Li/P) is from0.1:1 to 20:1.
 9. The method of claim 6, where the monomer is1,3-butadiene and comonomer is styrene.
 10. A functionalized polymerdefined by the Formula V:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, where R⁶ is abond or a divalent organic group, where R⁷ is a monovalent organicgroup, P is a phosphorus atom, π is a polymer chain, and ω is a hydrogenatom, a terminal functional group, or a multivalent coupling group. 11.A functionalized polymer defined by the Formula VI:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, where R⁶ is abond or a divalent organic group, where R⁷ is a monovalent organicgroup, P is a phosphorus atom, π is a polymer chain, and ω is a hydrogenatom, a terminal functional group, or a multivalent coupling group. 12.A vulcanizate comprising the cured product of the polymer of claims 10and 11, wherein the vulcanizate includes carbon black, silicon, orcarbon black and silica.